mpegvideo_probe: check slice order

Fixes: Enrique.mp3
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavformat/mpegvideodec.c

@@ -34,8 +34,9 @@
 static int mpegvideo_probe(AVProbeData *p)
 {
     uint32_t code= -1;
-    int pic=0, seq=0, slice=0, pspack=0, vpes=0, apes=0, res=0;
+    int pic=0, seq=0, slice=0, pspack=0, vpes=0, apes=0, res=0, sicle=0;
     int i;
+    uint32_t last = 0;
 
     for(i=0; i<p->buf_size; i++){
         code = (code<<8) + p->buf[i];
@@ -47,12 +48,21 @@ static int mpegvideo_probe(AVProbeData *p)
             case              0x1b6:
                                         res++; break;
             }
-            if (code >= SLICE_START_CODE && code <= 0x1af) slice++;
+            if (code >= SLICE_START_CODE && code <= 0x1af) {
+                if (last >= SLICE_START_CODE && last <= 0x1af) {
+                    if (code >= last) slice++;
+                    else              sicle++;
+                }else{
+                    if (code == SLICE_START_CODE) slice++;
+                    else                          sicle++;
+                }
+            }
             if     ((code & 0x1f0) == VIDEO_ID)   vpes++;
             else if((code & 0x1e0) == AUDIO_ID)   apes++;
+            last = code;
         }
     }
-    if(seq && seq*9<=pic*10 && pic*9<=slice*10 && !pspack && !apes && !res) {
+    if(seq && seq*9<=pic*10 && pic*9<=slice*10 && !pspack && !apes && !res && slice > sicle) {
         if(vpes) return AVPROBE_SCORE_MAX/8;
         else     return pic>1 ? AVPROBE_SCORE_MAX/2+1 : AVPROBE_SCORE_MAX/4; // +1 for .mpg
     }